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PCI: Create revision file in sysfs

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Currently the revision isn't available via sysfs/libudev thus if one wants
to know the value one needs to read through the config file, which can be
quite time-consuming because it wakes/powers up the device.

There are at least two userspace components which could make use the new
file: libpciaccess and libdrm.  The former wakes up _every_ PCI device,
which can be observed via glxinfo when using Mesa 10.0+ drivers.  The
latter, in association with Mesa 13.0, can lead to 2-3 second delays while
starting firefox, thunderbird or chromium.

Link: https://bugs.freedesktop.org/show_bug.cgi?id=98502
Tested-by: Mauro Santos <registo.mailling@gmail.com>
Signed-off-by: Emil Velikov <emil.velikov@collabora.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch
CC: Greg KH <gregkh@linuxfoundation.org>
This commit is contained in:
Emil Velikov 2016-11-21 16:24:49 -06:00 committed by Bjorn Helgaas
parent 1001354ca3
commit 702ed3be1b
3 changed files with 11 additions and 0 deletions
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7
Documentation/ABI/testing/sysfs-bus-pci
View file

@ -294,3 +294,10 @@ Description:
a firmware bug to the system vendor. Writing to this file a firmware bug to the system vendor. Writing to this file
taints the kernel with TAINT_FIRMWARE_WORKAROUND, which taints the kernel with TAINT_FIRMWARE_WORKAROUND, which
reduces the supportability of your system. reduces the supportability of your system.
What: /sys/bus/pci/devices/.../revision
Date: November 2016
Contact: Emil Velikov <emil.l.velikov@gmail.com>
Description:
This file contains the revision field of the the PCI device.
The value comes from device config space. The file is read only.

2
Documentation/filesystems/sysfs-pci.txt
View file

@ -17,6 +17,7 @@ that support it. For example, a given bus might look like this:
| |-- resource0 | |-- resource0
| |-- resource1 | |-- resource1
| |-- resource2 | |-- resource2
| |-- revision
| |-- rom | |-- rom
| |-- subsystem_device | |-- subsystem_device
| |-- subsystem_vendor | |-- subsystem_vendor
@ -41,6 +42,7 @@ files, each with their own function.
resource PCI resource host addresses (ascii, ro) resource PCI resource host addresses (ascii, ro)
resource0..N PCI resource N, if present (binary, mmap, rw[1]) resource0..N PCI resource N, if present (binary, mmap, rw[1])
resource0_wc..N_wc PCI WC map resource N, if prefetchable (binary, mmap) resource0_wc..N_wc PCI WC map resource N, if prefetchable (binary, mmap)
revision PCI revision (ascii, ro)
rom PCI ROM resource, if present (binary, ro) rom PCI ROM resource, if present (binary, ro)
subsystem_device PCI subsystem device (ascii, ro) subsystem_device PCI subsystem device (ascii, ro)
subsystem_vendor PCI subsystem vendor (ascii, ro) subsystem_vendor PCI subsystem vendor (ascii, ro)

2
drivers/pci/pci-sysfs.c
View file

@ -50,6 +50,7 @@ pci_config_attr(vendor, "0x%04x\n");
pci_config_attr(device, "0x%04x\n"); pci_config_attr(device, "0x%04x\n");
pci_config_attr(subsystem_vendor, "0x%04x\n"); pci_config_attr(subsystem_vendor, "0x%04x\n");
pci_config_attr(subsystem_device, "0x%04x\n"); pci_config_attr(subsystem_device, "0x%04x\n");
pci_config_attr(revision, "0x%02x\n");
pci_config_attr(class, "0x%06x\n"); pci_config_attr(class, "0x%06x\n");
pci_config_attr(irq, "%u\n"); pci_config_attr(irq, "%u\n");
@ -568,6 +569,7 @@ static struct attribute *pci_dev_attrs[] = {
&dev_attr_device.attr, &dev_attr_device.attr,
&dev_attr_subsystem_vendor.attr, &dev_attr_subsystem_vendor.attr,
&dev_attr_subsystem_device.attr, &dev_attr_subsystem_device.attr,
&dev_attr_revision.attr,
&dev_attr_class.attr, &dev_attr_class.attr,
&dev_attr_irq.attr, &dev_attr_irq.attr,
&dev_attr_local_cpus.attr, &dev_attr_local_cpus.attr,